Method and apparatus for mobility robustness optimization

Abstract

The present disclosure relates to methods and apparatuses for MRO in a communication system. According to some embodiments of the disclosure, a UE may: receive a UE information request message; and transmit a UE information response message in response to receiving the UE information request message. The UE information response message may include at least one of the following: a radio link failure (RLF) report associated with a multiple universal subscriber identity module (MUSIM) operation of the UE; or a successful handover report, wherein the handover may include a handover of the UE from a first radio access technology (RAT) to a second RAT for voice fallback.

1 . A user equipment (UE), comprising:
 at least one memory; and   at least one processor coupled with the at least one memory and configured to cause the UE to:
 receive a UE information request message; and 
 transmit a UE information response message in response to receiving the UE information request message, wherein the UE information response message comprises at least one of the following:
 a radio link failure (RLF) report associated with a multiple universal subscriber identity module (MUSIM) operation of the UE; or 
 a successful handover report, wherein the handover comprises a handover of the UE from a first radio access technology (RAT) to a second RAT for voice fallback. 
 
   
     
     
         2 . The UE of  claim 1 , wherein the UE further comprises a first USIM and a second USIM, and the UE is in a connected state in a first radio access network (RAN) associated with the first USIM; and
 wherein the at least one processor is coupled to the first USIM and the second USIM, and is configured to cause the UE to perform at least one of:
 prohibit initiating a reestablishment procedure in response to detecting an RLF associated with the first RAN when a timer for leaving without a response is running; 
 prohibit storing RLF information in response to detecting the RLF associated with the first RAN when the timer for leaving without a response is running; 
 store the RLF information in response to detecting the RLF associated with the first RAN when the timer for leaving without a response is not running; or 
 store the RLF information in response to detecting the RLF associated with the first RAN when the timer for leaving without a response is running. 
   
     
     
         3 . The UE of  claim 2 , wherein the RLF report associated with the MUSIM operation comprises the RLF information or both the RLF information and an indication, wherein the indication indicates that the timer for leaving without a response is running when the RLF is detected. 
     
     
         4 . The UE of  claim 1 , wherein the UE further comprises a first USIM and a second USIM, and the UE is in a connected state in a first radio access network (RAN) associated with the first USIM; and
 wherein the at least one processor is coupled to the first USIM and the second USIM, and is configured to cause the UE to:   transmit, to the first RAN, a UE assistant information message to request to leave the connected state in the first RAN; and   start a timer for leaving without a response in response to transmission of the UE assistant information message.   
     
     
         5 . The UE of  claim 4 , wherein the at least one processor is further configured to cause the UE to perform at least one of:
 prohibit executing a conditional handover (CHO) in response to a CHO execution condition being met when the timer for leaving without a response is running;   stop evaluating a CHO execution condition when the timer for leaving without a response is running; or   prohibit performing a handover (HO) command received from the first RAN when the timer for leaving without a response is running.   
     
     
         6 . The UE of  claim 5 , wherein the at least one processor is further configured to cause the UE to re-enter the connected state in the first RAN, and the UE information request message is received after re-entering the connected state in the first RAN; and
 wherein the RLF report associated with the MUSIM operation comprises at least one of the following:
 a first indication indicating that a CHO is not performed or indicating that a CHO is not performed when the timer for leaving without a response is running; 
 a second indication indicating that CHO evaluation is stopped when the timer for leaving without a response is running; or 
 a third indication indicating that a HO command is not performed or indicating that a HO command is received when the timer for leaving without a response is running. 
   
     
     
         7 . The UE of  claim 1 , wherein the at least one processor is configured to cause the UE to:
 receive a command for the handover from the first RAT to the second RAT, wherein the command is for voice fallback; and   successfully access a cell associated with the second RAT according to the command.   
     
     
         8 . The UE of  claim 7 , wherein the at least one processor is configured to cause the UE to store information associated with the handover from the first RAT to the second RAT in response to a trigger condition for reporting a successful handover report being met;
 wherein the UE information request message is received after successfully accessing the cell associated with the second RAT; and   wherein the successful handover report comprises at least one of the following:
 a voice fallback indication; or 
 information related to the cell associated with the second RAT. 
   
     
     
         9 . The UE of  claim 8 , wherein the information related to the cell associated with the second RAT comprises at least one of the following:
 a first indication indicating that a physical layer problem timer is started within a period after the handover from the first RAT to the second RAT; or   a second indication indicating that a timer associated with measurement report triggering is started within a period after the handover from the first RAT to the second RAT.   
     
     
         10 . The UE of  claim 7 , wherein the at least one processor is configured to cause the UE to prohibit storing information associated with the handover from the first RAT to the second RAT in response to a trigger condition for reporting a successful handover report being met. 
     
     
         11 . A first base station (BS), comprising:
 at least one memory; and   at least one processor coupled with the at least one memory and configured to cause the first base station to:
 transmit, to a user equipment (UE), a UE information request message; and 
 receive, from the UE, a UE information response message in response to transmitting the UE information request message, wherein the UE information response message comprises at least one of the following:
 a radio link failure (RLF) report associated with a multiple universal subscriber identity module (MUSIM) operation of the UE; or 
 a successful handover report, wherein the handover comprises a handover of the UE from a first radio access technology (RAT) to a second RAT for voice fallback. 
 
   
     
     
         12 . The first base station of  claim 11 , wherein the first BS is associated with a first radio access network (RAN), and
 wherein the RLF report associated with the MUSIM operation comprises information of an RLF between a second BS associated with the first RAN and the UE, and an indication which indicates that a timer for leaving without a response is running at the UE when the RLF occurs.   
     
     
         13 . The first base station of  claim 11 , wherein the first BS is associated with a first radio access network (RAN), and the RLF report associated with the MUSIM operation comprises at least one of the following:
 a first indication indicating that a conditional handover (CHO) is not performed at the UE or indicating that a CHO is not performed at the UE when a timer for leaving without a response is running at the UE;   a second indication indicating that CHO evaluation is stopped at the UE when the timer for leaving without a response is running at the UE; or   a third indication indicating that a handover (HO) command is not performed at the UE or indicating that a HO command is received at the UE when the timer for leaving without a response is running at the UE, wherein the HO command is transmitted from a second BS associated with the first RAN.   
     
     
         14 . The first base station of  claim 11 , wherein the first BS is associated with the second RAT, and the successful handover report comprises at least one of the following:
 a voice fallback indication; or   information related to a serving cell of the UE.   
     
     
         15 . A method performed by a user equipment (UE), the method comprising:
 receiving a UE information request message; and   transmitting a UE information response message in response to receiving the UE information request message, wherein the UE information response message comprises at least one of the following:
 a radio link failure (RLF) report associated with a multiple universal subscriber identity module (MUSIM) operation of the UE; or 
 a successful handover report, wherein the handover comprises a handover of the UE from a first radio access technology (RAT) to a second RAT for voice fallback. 
   
     
     
         16 . The method of  claim 15 , wherein the UE comprises a first USIM and the UE is in a connected state in a first radio access network (RAN) associated with the first USIM, and wherein the method further comprises:
 prohibiting initiating a reestablishment procedure in response to detecting an RLF associated with the first RAN when a timer for leaving without a response is running;   prohibiting storing RLF information in response to detecting the RLF associated with the first RAN when the timer for leaving without a response is running;   storing the RLF information in response to detecting the RLF associated with the first RAN when the timer for leaving without a response is not running; or   storing the RLF information in response to detecting the RLF associated with the first RAN when the timer for leaving without a response is running.   
     
     
         17 . The method of  claim 16 , wherein the RLF report associated with the MUSIM operation comprises the RLF information or both the RLF information and an indication, wherein the indication indicates that the timer for leaving without a response is running when the RLF is detected. 
     
     
         18 . The method of  claim 15 , wherein the UE comprises a first USIM and the UE is in a connected state in a first radio access network (RAN) associated with the first USIM, and wherein the method further comprises:
 transmitting, to the first RAN, a UE assistant information message to request to leave the connected state in the first RAN; and   starting a timer for leaving without a response in response to transmission of the UE assistant information message.   
     
     
         19 . The method of  claim 18 , further comprising at least one of:
 prohibiting executing a conditional handover (CHO) in response to a CHO execution condition being met when the timer for leaving without a response is running;   stopping evaluating a CHO execution condition when the timer for leaving without a response is running; or   prohibiting performing a handover (HO) command received from the first RAN when the timer for leaving without a response is running.   
     
     
         20 . A processor for wireless communication, comprising:
 at least one controller coupled with at least one memory and configured to cause the processor to:
 receive a user equipment (UE) information request message; and 
 transmit a UE information response message in response to receiving the UE information request message, wherein the UE information response message comprises at least one of the following:
 a radio link failure (RLF) report associated with a multiple universal subscriber identity module (MUSIM) operation of the UE; or 
 a successful handover report, wherein the handover comprises a handover of the UE from a first radio access technology (RAT) to a second RAT for voice fallback.